Method and apparatus for separating dolphin from tuna

ABSTRACT

A method and apparatus for using the primordial fear of dolphin of killer whales to separate dolphin from tuna. The sound of killer whale is recorded, digitized, edited and enhanced to produce digitally synthesized killer whale sounds. These digitally synthesized sounds of one or more feeding killer whale is played under water and in the vicinity of a mixed school of dolphin and tuna and as the dolphin leave said vicinity, catching the tuna in nets. A playback unit is selectively triggered on and off from a remote location.

This is a divisional of application Ser. No. 633,539, filed Dec. 28,1990, now U.S. Pat. No. 5,134,592.

The present invention relates to a method and apparatus for separatingcertain aquatic mammals from fish such as tuna and the like.

BACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION

In the past, there have been several techniques attempted to be utilizedby commercial tuna fishermen to separate dolphin from tuna. Tunafishermen in small boats in advance of the nets have attempted to chasethe dolphin away from the nets and this technique has resulted in theinjury and possible loss of life to tuna fishermen and still results insome dolphin being caught in tuna nets. Others have attempted explosionsin the water to frighten the dolphin.

The present invention utilizes the primordial fear of dolphin to killerwhale to separate dolphin from tuna. This permits the tuna to be caughtin tuna nets without the dolphin being captured in the tuna net.According to the invention, the sound of one or more killer whalefeeding is captured by a transducer, converted to digital sound and thenedited to edit out splashing sounds or other non-useful portions of therecording. In addition, the killer whale feeding sounds are enhanced byproducing more of them and, when such killer whales are in a feedingfrenzy, the sounds are recorded digitized, edited and enhanced and thenbroadcast in the sea water by a high power acoustic transducer tosimulate the feeding frenzy.

In the preferred embodiment, these enhanced feeding sounds of killerwhales are digitally stored and reproduced in an underwater transducer.The transducer (there may be a plurality of spaced transducers tosimulate more than one killer whale) is positioned ahead of a net whichis being used to capture the tuna. In another embodiment, thetransducer(s) is located between the net and the ship towing the net.Preferably, the transducer is located along the travel axis or path ofthe ship and the net.

DETAILED DESCRIPTION OF THE DRAWINGS

The above and other objects, advantages and features of the inventionwill become more apparent when considered with the followingspecification and accompanying drawings wherein:

FIG. 1 is a block diagram illustrating the capturing of the killer whalesounds; digitization thereof, editing and enhancement and recording, and

FIG. 2 illustrates a position of the transducers for converting thedigitally recorded killer whale feeding sounds to acoustic energy forcoupling into the salt water between the ship and the tuna nets andfrighten the dolphin away from the tuna.

DETAILED DESCRIPTION OF THE INVENTION

It is known that aquatic mammals living in the sea have over themillennium developed a primordial fear of predator aquatic animals andthat fish, such as tuna, which have no memory and thus have notdeveloped the same primordial fear that mammals have developed. Thus,while tuna may have certain immediate fear of being eaten by a killerwhale, for example, it's not nearly as strong as those senses developedin the dolphin. Other sea mammals such as sea lions, seals, otters, andthe like have similarly developed primordial fears of the feeding soundof killer whales, which is a sea predator that is capable of generatingthese sounds that generate the primordial fear in this higher order ofaquatic animals. The present invention seeks to synthesize the feedingsounds of predator aquatic animals such as the killer whale and use thesynthesized to separate tuna from dolphin. In other cases, this inducingof this primordial fear in aquatic animals that are desired to beprotected can induce them to shy away from danger areas and thus bylocating a transducer for introducing the feeding sounds of predatoraquatic animals at danger areas, causes them to travel away.

Referring to FIG. 1, a killer whale 10 is generating killer whalefeeding sounds which are indicated by pressure waves 11 as the killerwhale is feeding on fish 12. These soundwaves are picked-up bytransducer 13 which is a broadband transducer picking-up both infrasonicsounds as well as high frequency sounds over a wide spectrum and thesoundwaves are converted to electrical signals transmitted to anamplifier 14 and converted to a digital signal by analog-to-digitalconverter 15. This provides a digital rendition of the killer whalefeeding sounds which is edited in editor 16 to delete splashing sounds,and other non-useful portions of the digitized audio signal. The editeddigital signals of the killer whale feeding sounds are then enhanced inenhancing module 17. Enhancement may take the form of making the soundsmore forceful by repeating them at a higher rate (while maintaining thesame sound frequency spectrum). During this phase of the process ofproducing the synthesized killer whale feeding sounds, testing may bedone by playing the sounds in pools where captured dolphin, such asbottle-nosed dolphins are located, and by modifying the repetition rateas well as the energy levels it is possible to make the killer whalefeeding sounds more forceful and thus have more of an effect on thedolphin in inducing the primordial fear in the dolphin of the killerwhale. After the digital signals of the killer whale feeding sounds havebeen enhanced in enhancer 17, a record thereof is made in recorder 18such as on a tape 20, a disk 21 (magnetic or optical) or in anelectronic chip 22 such as a LSI ROM memory.

Referring now to FIG. 2, a tuna ship 25 tows one or more net 26 and hasa number of smaller ships or boats (not shown) which tend tuna nets 26.Positioned between the ship 25 and tuna net 26 are one or moretransducers 27 which are connected to a playback unit 28 and have one ofthe records 20, 21, 22 therein for driving the transducer 27. Transducer27, preferably is omni-directional but may be directional, and theplayback unit 28 may be selectively triggered on and off by a radiosignal from a transmitter 29 on the ship and received by a receiver 30.Receiver 30 triggers on the playback unit 28 on and off to selectivelyplayback the recorded killer whale sounds which are amplified andapplied to transducer 27 to thereby broadcast into the sea water thekiller whale sounds.

This causes the dolphin 31 which may be swimming in a mixed school oftuna 32 or slightly above or below the tuna to separate quickly from thetuna and thereby permit the tuna to be captured in the nets 26 free orsubstantially free of all dolphin.

While there has been shown and described a preferred embodiment of theinvention, it will be appreciated that other embodiments will be readilyapparent to those skilled in the art and it is desired to encompass suchobvious modification and variations within the spirit and scope of theclaims appended hereto.

What is claimed is:
 1. In a tuna fishing system wherein a fishing vesselutilizes nets to catch tuna therein, a method for using the primordialfear of dolphin of killer whales to separate dolphin from tuna so thatthe tuna can be caught in the nets free of dolphin, comprising providinga digitally synthesized, edited and enhanced sound of feeding killerwhale, including, infrasonic sounds, providing a transducer, playingsaid digitally synthesized sound of feeding killer whale on saidtransducer under water and in the vicinity of a mixed school of dolphinand tuna and as the dolphin leave said vicinity, catching the tuna innets.
 2. The method defined in claim 1 wherein said transducer islocated between the net and the vessel.